Coated fertilizer

ABSTRACT

TENACIOUS COATINGS OF FERTILIZER SUPPLEMENTS ARE APPLIED TO GRANULAR HIGH ANALYSIS FERTILIZERS, BY ADDING, IN ORDER, MINOR AMOUNTS OF MINERAL OIL AND OF AQUEOUS CALCIUM LIGNOSULFONATE AND THEN SUBSTANTIAL AMONTS OF FERTILIZER SUPPLEMENTS, MAINTAINING THE GRANULES IN MOTION DURING AND AFTER ADDITION UNTIL THE ADDED MATERIAL UNIFORMLY COATS THE GRANULES.

3,697,245 COATED FERTILIZER Joseph T. Dilday, 3971 Glenmere Road, NorthLittle Rock, Ark. 72116 No Drawing. Original application Apr. 16, 1969,Ser.

No. 816,808. Divided and this application Aug. 12,

1970, Ser. No. 63,315

Int. Cl. C05c 9/00 US. Cl. 71-28 3 Claims ABSTRACT OF THE DISCLOSURETenacious coatings of fertilizer supplements are applied to granularhigh analysis fertilizers, by adding, in order, minor amounts of mineraloil and of aqueous calcium lignosulfonate and then substantial amountsof fertilizer supplements, maintaining the granules in motion during andafter each addition until the added material uniformly coats thegranules.

This application is a division of US. Ser. No. 816,808 filed Apr. 16,1969, now US. Pat. 3,580,715, issued May 25, 1971.

This invention relates to coated high analysis fertilizer granules andto a process for their production. More particularly, it relates totenacious coatings of fertilizer supplements on granules of highanalysis fertilizers.

Granular mixed high analysis fertilizers are commercially availableammonium phosphates, ammonium sulfate, urea and mixtures thereof, withor without potassium salts, particularly potassium chloride. Analyses ofthese fertilizer materials is commonly expressed as the content of N, PK 0 and referred to as N-P-K. Examples of commercial granular highanalysis fertilizers include 6-24-24, 11-48-0, 13-13-13, 16-16-16,18-46-0 and 30-10-10. Commercial urea similarly is 46-0-0. All of thesematerials are sized to pass 6 mesh and to be substantially all retainedon 40 mesh US. Standard screens. These materials are referred to in thisspecification and claims as high analysis fertilizers.

Fertilizer supplements are desirably provided for special purposes whichcan be accomplished by one application to the soil by combining thesupplement with the fertilizer. It is especially advantageous to combinewith high analysis fertilizers one or more fertilizer supplementsselected from the group consisting of sulfur, micronutrients andpesticides. However, fertilizer supplements are finely divided materialsand difliculties arise in combining these supplements with the granulesto provide products which are of'uniform composition and which remain ofuniform composition in handling, shipping and use.

Elemental sulfur is commonly employed in mixtures with fertilizersespecially for use in western United States where soils are frequentlydeficient in this plant nutrient. Sulfur also serves as a fungicide,soil conditioner, neutralizes alkalinity and solubilizes othernutrients. Sulfur applied as a coating on fertilizer particles reducestheir caking tendency and it reduces the rate of release of very solublefertilizers, for example, urea, to the soil. In this way, more of thesesoluble materials are absorbed and utilized by the crop.

Micronutrient compounds are also fertilizer supplements advantageouslycoated on granular fertilizers. The micronutrient elements are usuallyconsidered to be iron, manganese, molybdenum, boron, copper, zinc andchlorine. These elements are usually supplied as salts or oxidescontaining the elements in the cations or anions. Suitable salts are,for example, sulfates, nitrates, chlorides, molybdates or borates. Zincis frequently supplied as the oxide.

Uhite'clStates Patent 0 Pesticides are also fertilizer supplements whichare advantageously incorporated with granular fertilizers. They serve tocontrol fungi, nematodes, insects and other pests with the applicationof granular fertilizers to feed the crops. Examples of suitablepesticides include penta: chloronitrobenzene, l-naphthylN-methylcarbamate, zinc ethylene bis-dithiocarbamate, phosphate andthiophosphate esters, e.g., 0,0-dimethyl S-(1,2-dicarbethoxyethyl)phosphorodithioate among others.

The fertilizer supplements are generally available in finely dividedform or are advantageously finely ground so that most passes 200 meshUS. Standard screens. The preparation of satisfactory coatings offertilizer supplements on granular fertilizer compositions must overcomethe difficulty that the powdered supplements do not adhere tightly tofertilizer particles. The supplements, simply blended with thefertilizer particles, tend to separate and settle in spite of thoroughmixing. Separation and settling are aggravated by shipping and handling.

Various binders are known to the art to improve the adherence of finelydivided supplements to granular fertilizers. US. Pat. No. 3,295,950shows oils and waxes, No. 3,313,613 shows urea-formaldehyde resins, No.3,313,615 shows gilsonite and No. 3,353,949 shows sugars and alkalimetal lignosulfonates as binders. US. Pat. 3,100,698 describesmelt-blending of sulfur and urea. However, this requires specializedequipment and greater costs.

However, there is still a need in the art for an improved method ofcoating granular fertilizers with fertilizer supplements to providecoated fertilizers which are uniformly coated, free-flowing, stable instorage and use and which provide immediate availability of thesupplements for leaching by the soil while still retarding thedissolution and loss of soluble fertilizer components.

According to this invention, novel compositions comprising granularfertilizers having a tightly adherent coating of fertilizer supplementare prepared by:

1) Maintaining the granules in motion while adding from 0.5 to 5% byweight, based on the total of fertilizer and supplement,-of mineral oilof lubricating viscosity and maintaining said motion until said oiluniformly coats said granules;

(2) Adding aqueous calcium lignosulfonate solution containing from 20 to70% of calcium lignosulfonate solids to provide from 0.1 to 5% byweight, based on the total of fertilizer and supplement of said calciumlignosulfonate solids and maintaining said motion until saidlignosulfonate uniformly coats said particles; and

(3) Adding from 1 to 20% by weight, based on the total of saidfertilizer and supplement, of fertilizer supplement passing 200 mesh US.Standard screens and maintaining said motion until said supplementuniformly coats said particles.

In the process of this invention,- the order of addition of theparticular materials is critical to successful accomplishment. When theprocess is practiced using the materials specified, outstanding productsare obtained. When the lignosulfonate is added prior to the oil, thesticky, viscous lignosulfonate is substantially unspreadable and theparticles agglomerate in large aggregates. The particles are notuniformly coated and the resulting bald spots cause serious caking instorage. For this reason, addition of the oil prior to the calciumlignosulfonate is necessary to obtain uniform spreading of thelignosulfonate'and to produce a uniform coating of supplement. Omissionof the oil fails to achieve the products of the process of thisinvention. Oil alone as binder is unsatisfactory. The oil graduallytransfers from the finely divided supplement and penetrates the granulesof fertilizer, loosening the supplement particles which then separateand segregate from the larger granules during handling. Such looseningdoes not occur using both oil and calcium lignosulfonate according tothe present invention. Addition of the lignosulfonate to a preformed drymixture of supplement and granules of fertilizer similarly results inthe formation of unmanageable lumps and non-uniform coating of thegranules. The alkali metal or ammonium lignosulfouates are notequivalents of the calcium lignosulfonate used in this invention and donot have the binding ability of the calcium lignosulfonate to produceuniformly coated particles.

Practice of they process of this invention as described results insubstantially complete adherence of the sup plement to the fertilizergranules without loss and without the necessity of separating the coatedproduct from non-adherent particles. The fertilizer granules areuniformly coated without any bald spots and the coating has outstandingresistance to attrition and separation from the fertilizer granulesduring normal or even unusual handling and/or shipment. In storage, thecoated granules are substantially non-caking, even under extendedstorage at elevated temperatures under extreme pressures due to highstacking of bags.

The process of this invention is carried out at ambient temperatures andno heating or cooling is required. Mechanical agitation tends to addminor amounts of heat to the compositions but this is negligible and isnot an essential part of the invention.

The products of this invention when distributed on the soil provide thefertilizing benefit of their N-P-R content together with acidificationof the soil when sulfur is the supplement, providing necessarymicronutrients when they are incorporated and pesticidal action when thesupplement is a pesticide in whole or in part.

Supplements suitable for use in the process of this invention must befine particles passing 200 mesh U.S. Standard screens. For mostadvantageous results, the sup,- plements are even finer. Cloud brandsulfur, which is commercially available and has 95% or more passing 325mesh, is particularly suitable. The micronutrients are generallyavailable in finely divided form. They are advantageously incorporatedwith sulfur or with pesticides in the coating formed according to thisinvention. They are addedat the time the sulfur or pesticide is added orthey are suitably mixed with the sulfur before adding.

The amount of supplement is suitably from 1 to 20% of the totalcomposition. Sulfur alone suitably forms the coating in these amounts.Micronutrients and pesticides are preferably used in lesser amounts fromabout 0.1 to of the compositions.

Mineral oil'of lubricating viscosity in the present specification andclaims means oils having a viscosity from about 400 to 500 S.S.U. at 100F. and include, for example, No. 2 Diesel fuel oil, light and mediumviscosity lubricating oils, neutral oils and used motor oils. Usedmotor. oil is available cheaply in large quantities and is especiallyadvantageous. Its use helps to ameliorate a disposal problem. The amountof oil, based on the total of fertilizer and sulfur is suitably fromabout 0.5 to 5%. Less than 0.5% may be insufficient to coat the granulesand more than 5% is unnecessary and may strike through paper bags inwhich the product is stored- The calcium lignosulfonate used in theprocess of this invention is a by-product of the lime process of woodpulping and is more particularly described as water-soluble, anionic,surface-active derivatives of lignin containing wood sugar derivatives.Norlig 41 is one such commercial product. Also available commerciallyare alkali metal and ammonium lignosulfonates but these are distinctlyinferior to calcium lignosulfonate in binding ability and are notequivalents in the process of this invention. The calcium lignosulfonateis used in the form of aqueous solutions containing from about 20 to 70%of calcium lignosulfonate. Commercial products usually contain 25%, 50%,55%, or 60% solids. According to the process of this 4 invention, theaqueous calcium lignosulfonate is added to the mixture of oil andfertilizer particles in amounts suflicient to provide from 0.1 to 5% ofcalcium lignosulfonate solids based on the total of fertilizer andsupplement. Less than 0.1% may be insufficient for complete adherence oflarger amounts of sulfur and more than 5% is unnecessary and may resultin a somewhat sticky, less desirable product.

EXAMPLE I Twenty five pounds of urea prills were coated with 10% sulfur.The prills were tumbled in a cement mixer while adding 1%, based on thesulfur and urea of used motor oil. After tumbling for 1 /2 minutes, 1%of a 50% aqueous calcium lignosulfonate was added and tumbling wascontinued for one minute. Ten percent of Cloud sulfur, 98% passing 325mesh, was added with additional tumbling for two minutes. All of thesulfur adhered to the prills and on screening less than 1% of the sulfurwas shaken from the prills. Applied to the soil at rates of 200 and 400pounds per acre, these coated prills fertilized crops of cotton, corn,wheat and soybeans and served to acidify the soil.

Repeating Example I using sodium lignosulfonate or ammoniumlignosulfonate for the calcium lignosulfonate, the coating was unevenand mottled with bare spots.

Repeating Example I omitting the oil, the prills agglomerated badly,were incompletely coated and caked badly.

When the procedure of Example I was varied by omitting the oil and bymixing the sulfur with the prills, then adding sodium lignosulfonate,mottled prills with a high proportion of bare spots were produced andthey caked badly.

EXAMPLE II,

A larger batch of sulfur coated urea prills was prepared by theprocedure described in Example I using the quantities:

The product retained substantially all of the sulfur. Analysis showed40.5% nitrogen and 10% sulfur. The prills were bagged and the bags werestacked 10 deep in warehouse storage for 3 months. When opened, even thebottom bags were completely free-flowing.

EXAMPLE III Granular Ammo-Phos, a commercial fertilizer mixturenominally analyzing '6'2424 (for nitrogen, P 0 and K 0) was coated with5% sulfur by the procedure shown in Example I using the quantities.

Pounds 6-24-24 1860 Used motor oil 20 Calcium lignosulfonate (50%) 20*Cloud" sulfur 100 Substantially all of the sulfur was tightly adherenton the fertilizer particles and the product analyzed 5% S. Actualanalysis for NPK was 5.622.322.3%. The product was substantiallynon-caking in storage.

EXAMPLE IV Granular Ammo-Phos, a commercial fertilizer mixture nominallyanalyzing 13-43-13 (for nitrogen, P 0 and K 0) was coated with 15.5% ofpentachloronitrobenzene by the procedure shown in Example I, using thefollowing percentages:

Percent 13-13-13 75.3 Used motor oil 3.0 Calcium lignosulfonate (50%)1.0 Terraclor 75W 20.7

The Terraclor 75W is a wettable powder containing 75% ofpentachloronitrobenzene. All the Terraclor was tightly adherent on thefertilizer particles. Actual analysis for N-P-K was 9.8-9.8-9.8. Theproduct was substantially non-caking in storage.

EXAMPLE V Granular Ammo-Phos, a commercial fertilizer mixture nominallyanalyzing 13-13-13 (for nitrogen, P and K 0) was coated with ofpentachloronitrobenzene and 4% of naphthyl N-methylcarbamate by theprocedure shown in Example I, using the following percentages The Sevin80W is a wettable powder containing 80% of l-naphthyl N-methylcarbamate.All the Terraclor and Sevin was tightly adherent on the fertilizerparticles. Actual analysis for N-P-K was 10.1-10.l-10.1. The product wassubstantially non-caking in storage.

What is claimed is:

1. As a composition of matter, granules of high analysis fertilizerhaving a tightly adherent coating of fertilizer supplement bound byminor amounts of mineral oil of lubricating viscosity and calciumlignosulfonate solids.

2. A composition of matter as claimed in claim 1 in which said granulesof high analysis fertilizer are urea prills and said supplement issulfur.

3. A composition of matter as claimed in claim 1 in which said highanalysis fertilizer amounts to from to 99% and said supplement amountsto from 1 to 20% based on the total of said supplement and saidfertilizer and each of said oil and said calcium lignosulfonate solidsamount to from 0.1 to 5% based on the total of said fertilizer andsupplement.

References Cited UNITED STATES PATENTS 3,353,949 11/1967 Nau 71-1 X3,357,813 12/1967 Elson 7123 3,295,950 l/l967 Blouin et al 7l--28 X3,313,613 4/1967 Green 71-64 F X REUBEN FRIEDMAN, Primary Examiner R. M.BARNES, Assistant Examiner US. Cl. X.R. 7164 E, 64 F

